107
5
5 Glycerol tertiary butyl ether are
interesting as diesel additives, which
reduce the fine dust content, and as
gasoline additives, which increase the
octane number.
5 Glycerol octadienylether can be
used as emulsifiers or surfactants after
hydrogenation.
5 Glycerol acetals and ketals are
produced by reaction with aldehydes
such as formaldehyde or ketones such
as acetone. They are used as solvents
or fragrances and can be used as diesel
additives.
5 Glycerol can be catalytically
dehydroxylated to the two propanediols1,2-propanediol and 1,3-propanediol,
respectively. Biocatalytic processes are
particularly promising.
5 Glycerol can react with hydrogen chloride
to form dichloropropanol, which is
converted into epichlorohydrin with
sodium hydroxide solution. This is a
reversal of the old glycerol synthesis
process from propene via allyl chloride
and epichlorohydrin. Epichlorohydrin is
of great importance for the synthesis of
epoxy resins.
5 In glycerol oxidation, the oxidation
of the secondary hydroxyl group is
of particular interest: The result is
dihydroxyacetone, which is used as
a self-tanning agent in cosmetics. By
catalytic oxidation of a primary hydroxyl
group, glycerol aldehyde, glyceric acid
and tartronic acid can be formed.
5 Catalytic dehydration of glycerol
produces acrolein, which can be further
oxidized to acrylic acid. Acrylic acid is
of great importance for the synthesis of
polyacrylic acid and polyacrylates.
5 Glycerol can also be decomposed into
synthesis gas, a mixture of carbon
monoxide and hydrogen. Three process
variants are currently being investigated
in which decomposition takes place
in the gas phase, in the liquid phase
or in supercritical water. Synthesis gas
is therefore an interesting secondary
Summary (Take-Home Messages)
5 Glycerol is a polar, highly viscous and
boiling liquid. It is non-toxic and strongly
hygroscopic.
5 Various operations can be combined
to purify glycerol, such as evaporation,
prepurification by coagulation,
distillation, ion exchange and bleaching
(by adsorption on active carbon). Ion
exchange is energetically more favorable
than distillation. However, the ion
exchange unit cannot process glycerol
from saponification with a high salt
content.
5 Glycerol can also be produced
synthetically from propene. The two
synthesis routes via allyl chloride or allyl
alcohol are no longer important today.
5 Glycerol has long been used directly
in numerous applications, e.g. in
pharmaceutical products, in cosmetics, as
a humectant in tobacco, as a sweetener
in the food industry or as a plasticizer in
regenerated cellulose.
5 Some technical applications of glycerol
have also been known for decades, e.g.
as a crosslinking polyol in polyurethane
foams or alkyd resins.
5 The available amount of glycerol
sharply increased in recent years as a
result of biodiesel production; the price
of glycerol decreased accordingly.
This makes glycerol interesting for new
applications and new downstream
products.
5 Important glycerol derivatives are
glycerol esters. Glyceryl trinitrate,
acetins, mono- and diglycerides as well as
triglycerides with a special distribution of
fatty acids have to be mentioned here.
5 Glycerol ether include oligoglycerols,
highly branched polyglycerols, glycerol
tertiary butyl ether obtained by
reaction with isobutene and glycerol
octadienyl ether accessible by catalytic
telomerization.
5 The oligoglycerols are further processed
into oligoglycerol esters, which are used
in cosmetics as non-ionic surfactants.
5.9 · From Glycerol to Synthesis Gas
5
5 Glycerol tertiary butyl ether are
interesting as diesel additives, which
reduce the fine dust content, and as
gasoline additives, which increase the
octane number.
5 Glycerol octadienylether can be
used as emulsifiers or surfactants after
hydrogenation.
5 Glycerol acetals and ketals are
produced by reaction with aldehydes
such as formaldehyde or ketones such
as acetone. They are used as solvents
or fragrances and can be used as diesel
additives.
5 Glycerol can be catalytically
dehydroxylated to the two propanediols1,2-propanediol and 1,3-propanediol,
respectively. Biocatalytic processes are
particularly promising.
5 Glycerol can react with hydrogen chloride
to form dichloropropanol, which is
converted into epichlorohydrin with
sodium hydroxide solution. This is a
reversal of the old glycerol synthesis
process from propene via allyl chloride
and epichlorohydrin. Epichlorohydrin is
of great importance for the synthesis of
epoxy resins.
5 In glycerol oxidation, the oxidation
of the secondary hydroxyl group is
of particular interest: The result is
dihydroxyacetone, which is used as
a self-tanning agent in cosmetics. By
catalytic oxidation of a primary hydroxyl
group, glycerol aldehyde, glyceric acid
and tartronic acid can be formed.
5 Catalytic dehydration of glycerol
produces acrolein, which can be further
oxidized to acrylic acid. Acrylic acid is
of great importance for the synthesis of
polyacrylic acid and polyacrylates.
5 Glycerol can also be decomposed into
synthesis gas, a mixture of carbon
monoxide and hydrogen. Three process
variants are currently being investigated
in which decomposition takes place
in the gas phase, in the liquid phase
or in supercritical water. Synthesis gas
is therefore an interesting secondary
Summary (Take-Home Messages)
5 Glycerol is a polar, highly viscous and
boiling liquid. It is non-toxic and strongly
hygroscopic.
5 Various operations can be combined
to purify glycerol, such as evaporation,
prepurification by coagulation,
distillation, ion exchange and bleaching
(by adsorption on active carbon). Ion
exchange is energetically more favorable
than distillation. However, the ion
exchange unit cannot process glycerol
from saponification with a high salt
content.
5 Glycerol can also be produced
synthetically from propene. The two
synthesis routes via allyl chloride or allyl
alcohol are no longer important today.
5 Glycerol has long been used directly
in numerous applications, e.g. in
pharmaceutical products, in cosmetics, as
a humectant in tobacco, as a sweetener
in the food industry or as a plasticizer in
regenerated cellulose.
5 Some technical applications of glycerol
have also been known for decades, e.g.
as a crosslinking polyol in polyurethane
foams or alkyd resins.
5 The available amount of glycerol
sharply increased in recent years as a
result of biodiesel production; the price
of glycerol decreased accordingly.
This makes glycerol interesting for new
applications and new downstream
products.
5 Important glycerol derivatives are
glycerol esters. Glyceryl trinitrate,
acetins, mono- and diglycerides as well as
triglycerides with a special distribution of
fatty acids have to be mentioned here.
5 Glycerol ether include oligoglycerols,
highly branched polyglycerols, glycerol
tertiary butyl ether obtained by
reaction with isobutene and glycerol
octadienyl ether accessible by catalytic
telomerization.
5 The oligoglycerols are further processed
into oligoglycerol esters, which are used
in cosmetics as non-ionic surfactants.
5.9 · From Glycerol to Synthesis Gas